Epitope Capsid-Incorporation: New Effective Approach for Vaccine Development for Chagas Disease

Qiana L Matthews,Maria F Lima,Fernando Villalta,Anitra L Farrow,Linlin Gu,Shruti S Sakhare,Alexandre Krendelchtchikov,Pius Nde,Girish Rachakonda,Siddarth Pratap,Steffanie Sabbaj

doi:10.20411/pai.v1i2.114

Qiana L Matthews, Maria F Lima + Show 9 more

Open Access

https://doi.org/10.20411/pai.v1i2.114

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Abstract

Background:Previously we reported that a hexon-modified adenovirus (Ad) vector containing the invasive neutralizing epitope of Trypanosoma cruzi (T. cruzi) trypomastigote gp83 (Ad5-gp83) provided immunoprotection against T. cruzi infection. The purpose of this work was to design an improved vaccine for T. cruzi using a novel epitope capsid incorporation strategy. Thus, we evaluated the immunoprotection raised by co-immunization with Ad5-gp83 and an Ad vector containing an epitope (ASP-M) of the T. cruzi amastigote surface protein 2.Methods:Protein IX (pIX)-modified Ad vector (Ad5-pIX-ASP-M) was generated, characterized, and validated. C3H/He mice were immunized with Ad5-pIX-ASP-M and Ad5-gp83 and the cell-mediated responses were evaluated by enzyme-linked immunospot (ELISPOT) assay and intracellular staining. Immunized mice were challenged with T. cruzi to evaluate the vaccine efficacy.Results:Our findings indicate that Ad5-pIX-ASP-M was viable. Specific CD8+ T-cell mediated responses prior to the challenge show an increase in IFNγ and TNFα production. A single immunization with Ad5-pIX-ASP-M provided protection from T. cruzi infection, but co-immunizations with Ad5-pIX-ASP-M and Ad5-gp83 provided a higher immunoprotection and increased survival rate of mice.Conclusions:Overall, these results suggest that the combination of gp83 and ASP-M specific epitopes onto the capsid-incorporated adenoviruses would provide superior protection against Chagas disease as compared with Ad5-gp83 alone.

Highlights

Chagas disease is a neglected disease that affects 8–15 million people in Latin America
The modified Ad vector, referred to as Ad5-Protein IX (pIX)-ASP-M (Figure 1A), contains the immunodominant CD8+ T-cell epitope (TEWETGQI) from the medial region of amastigote protein 2 (ASP-2) [36] as well as His6 and Flag (DYKDDDDK) epitopes incorporated into the minor Ad capsid protein IX (Figure 1A, construct 3)
Two weeks after homologous vector reboost immunization, as shown in the immunization schedule (Figure 3A), C3H/He mice peripheral blood mononuclear cells (PBMCs) were evaluated for IFNγ production by enzyme-linked immunospot (ELISPOT) following stimulation with mitogen (PMA/ionomycin), or ASP-M peptide, presenting putative binding sites to MHC class I (H-2Kk) [36] and to HLA-A* 32:05, HLA-A* 32:08, HLA-A* 02:87, HLA-A* 32:06, and HLA-A* 32:20, that we identified using NetMHCpan [37], which are alleles frequent in Hispanic populations, and to 10 additional HLA-A* 02 and 32 alleles

Summary

Introduction

Chagas disease is a neglected disease that affects 8–15 million people in Latin America. 2–7 million people with Chagas disease live in North America [3]. Chagas-infected individuals represent a $7 billion/year burden worldwide [4]. The existing drugs are toxic and have limited efficacy and recent clinical trials with new drugs (posaconazole and ravuconazole) failed [5, 6]. We reported that a hexon-modified adenovirus (Ad) vector containing the invasive neutralizing epitope of Trypanosoma cruzi (T. cruzi) trypomastigote gp (Ad5-gp83) provided immunoprotection against T. cruzi infection. We evaluated the immunoprotection raised by co-immunization with Ad5-gp and an Ad vector containing an epitope (ASP-M) of the T. cruzi amastigote surface protein 2

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